1. Field of the Invention
The present invention relates to a vehicle air conditioning apparatus.
2. Description of Related Art
Vehicle air conditioning apparatuses include a transverse-mounted type having a layout in which a blower unit having a blower and a heat exchanging unit having a cooling heat exchanger are arranged in a lateral direction of a vehicle (see JP-A-2006-168656, for example) and a vertically-mounted type having a layout in which the blower unit and the heat exchanging unit are arranged in a vertical direction (see JP-A-2001-158217, for example).
In the vehicle air conditioning apparatus of the transverse-mounted type, a technology for adjusting an air-velocity distribution of air flowing into a heat exchanger by providing projecting portions which project perpendicularly to an air-inflow surface on an opposed wall surface which opposes the air-inflow surface of the heat exchanger is disclosed (for example, see JP-A-2009-166714). A technology for uniformizing an air-velocity distribution on a downstream side of a diffuser portion by providing a projection for generating vertical whirl on the diffuser portion having a suddenly-enlarged inflow channel is disclosed (see JP-A-2011-122517, for example).
A technology for reducing an aerodynamic sound generating by air turbulence by providing a plurality of projections on the wall surface of the air channel is disclosed (for example, see JP-A-2013-52808, for example).
When a cross-sectional area of an air channel is enlarged, burble which is an air flow separated from an inner wall surface of a case is generated. The burble forms a whirl flow, and the whirl flow may cause a noise. In JP-A-2009-166714, JP-A-2011-122517, and JP-A-2013-52808, technologies for adjusting the air-velocity distribution or reducing an aerodynamic sound by providing projections on the inner wall surface of the case are disclosed. However, a technology for reducing the noise caused by the burble is not disclosed.